Na+/K+-ATPASEによるナトリウムイオンの放出には,3つの異なる連続的なステップがあります
M Holmgren1, J Wagg, F Bezanilla
1The Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. miguel_holmgren@hms.harvard.edu
Nature
|March 8, 2000
まとめ
ナトリウム・カリウムポンプ (Na+/K+ポンプ) は3個のナトリウムイオンを連続的に放出します. 高速の電圧ジャンプは,電荷の移動の3つの異なる相を明らかにし,イオン放出機構を詳細に説明しました.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- メンブレーン輸送 メンブレーン輸送
背景:
- Na+/K+ポンプは,細胞イオングラデーションの維持に関与する重要なP型ATPアゼである.
- P型ATPases内のイオンオークスルーションとデオークスルーションのメカニズムは完全に理解されていません.
- カリウム欠乏Na+/K+ポンプの活動には,電源性ナトリウム転位のステップが含まれています.
研究 の 目的:
- Na+/K+ポンプによるナトリウムイオンの連続的な解封と放出を解明する.
- Na+/K+ポンプの形状動態の調節における膜電位の役割を調査する.
- ナトリウムイオン転位中の安定状態前の電荷の動きを特徴付けるために.
主な方法:
- Na+/K+ポンプの形状の変化を誘導するために高速電圧クランプ技術を使用しました.
- 電圧の乱れから生じる安定状態前の電荷の動きを分析した.
- イオン放出の数と順序を決定するための量化された電荷成分.
主要な成果:
- 電圧の跳ね上がった時の安定状態前の電荷の動きにおいて,3つの異なるリラックスフェーズが観察されました.
- これらの相は,3つのナトリウムイオンの解封と放出に対応することを示した.
- 3つのナトリウムイオンを細胞外空間へ放出するための連続的な1つずつ放出メカニズムを確立した.
結論:
- Na+/K+ポンプは,定義された順序で連続してナトリウムイオンを放出します.
- 高速電気生理学は,イオン誘導性ATPアゼの一時的な状態についての洞察を提供します.
- これらのメカニズムを理解することは,細胞イオンホメオスタシスとポンプ機能を理解するために不可欠です.
関連する概念動画
01:47Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps that are embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they...
01:29Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they would not...
01:31ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
01:34ATP Driven Pumps II: P-type Pumps
The P-type pumps are a large family of integral membrane transporter ATPases. They are divided into five major types based on substrate specificity, from I to V.
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
01:31ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
01:29Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they would not...